Modular soft starter

ABSTRACT

Modular soft starters are disclosed having a plurality of soft starter modules with stacked SCRs and heat sinks for accommodating a single phase of a three phase motor, where the modules may be connected serially for starting each phase of a higher voltage motor, and where the modules can be mounted in a cabinet in a variety of different orientations to facilitate optimized cabinet space utilization.

REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of U.S. ProvisionalPatent Application Ser. No. 60/883,837, filed Jan. 8, 2007, entitledMODULAR SOFT STARTER, the entirety of which is hereby incorporated byreference.

FIELD OF THE INVENTION

The present invention relates generally to electrical motors and moreparticularly to soft starters for electric motors. In general, motordrive systems are employed in medium voltage motor drives and otherapplications in which electrical power is converted for driving electricmotors or other loads. These systems are typically housed in cabinets toprotect the system components from dirt or other contaminants as well asto prevent exposure of operating personnel to high voltages and currentspresent inside the cabinet. In this respect, medium voltage motor drivestypically include transformers, contactors, switches, and other highpower electronic devices that may include exposed terminals carryingtens or hundreds of amps and which may be at hundreds or even thousandsof volts potential with respect to ground. Closed cabinetry thus servesto prevent inadvertent contact by operators or other personnel with livecomponents of motor drives and other power conversion systems duringnormal system operation.

Soft starters are sometimes referred to as solid state motor starters,and are operable to control the starting and stopping of electricalmotors by selectively providing power from a power source to theindividual motor leads using switching devices such as SiliconControlled Rectifiers (SCRs), thyristors, or other solid state powerswitches. Soft starters may be used to power an induction motor duringstarting and stopping, with the soft starter bypassed during normaloperation in which the motor is driven from another power source such asa Variable Speed Drive (VSD). In general, soft starters are employed tomitigate large startup currents that would otherwise occur if the motorwere energized from stand still by connection to line power. As themotor speed gradually increases, the motor terminal voltage iscontrolled automatically till the motor reaches near full speed, atwhich point the soft start can be bypassed.

The various motor drive components including soft starters are typicallyhoused in an industrial cabinet type enclosure. The space occupied bysoft starters and other drive components needs to be economized in orderto conserve space in a given cabinet or to potentially reduce therequired cabinet size. In the many possible motor drive applications,moreover, soft starters of various voltage ratings are needed for usewith different motor sizes. Thus, there is a need for improved motorsoft starters by which a variety of different motor soft starters can beconstructed having appropriate voltage and power ratings for a givenapplication, and by which the soft starter can be positioned indifferent cabinet sizes and configurations without occupying excessivecabinet space.

SUMMARY

Various aspects of the present invention are now summarized tofacilitate a basic understanding of the invention, wherein this summaryis not an extensive overview of the invention, and is intended neitherto identify certain elements of the invention, nor to delineate thescope thereof. Rather, the primary purpose of this summary is to presentsome concepts of the invention in a simplified form prior to the moredetailed description that is presented hereinafter.

The invention relates to motor soft starter modules that are operable topower a motor by selectively connecting power from a power source via aline terminal with the motor leads. The modules may be of any suitablepower rating, such as 2400 volts, where a module is provide for eachmotor phase, such as three modules for a three-phase induction motor.For higher motor voltage requirements, multiple modules can be connectedin series for each motor phase, thereby allowing a single module designor a relatively small number of module designs to be employed toconstruct a large number of different motor soft starter configurations.The modules, moreover, have highly adaptable mounting features allowingorientation of each module in a number of different ways within a givencabinet, thereby facilitating the construction of any desired motordrive/soft starter system while minimizing the cabinet space required.

The individual modules include a first switching device, such as an SCRor other semiconductor based switch having a first terminal (e.g., ananode) coupled with a module load terminal and a second terminal (e.g.,cathode) coupled with a line terminal, as well as a second switchingdevice having a first terminal electrically coupled with the lineterminal and a second terminal electrically coupled with the loadterminal. The switches are operated by a driver apparatus, such as oneor two driver boards that provide switching control signals to theswitches. Each module includes a housing comprised of two housingstructures mounted to one another to define an interior cavity in whichthe switches are mounted and allowing for external access to the loadterminal and the line terminal, where one or both of the housingstructures provide driver support structures for mounting the driverapparatus to the housing. The switches may be arranged in a clampedstack with intervening heat sinks with the stack arrangement mounted inthe cavity of the housing.

The housing further includes two or more module mounting structureslocated on one or both housing structures that allow the assembledhousing to be mounted to a flat structure such as a cabinet wall, floor,ceiling, etc. with either the module top, bottom, or side generallyparallel to the flat structure. The module mounting structures in oneimplementation include sets of flanges on one or both of the housingstructures that provide holes and/or slots allowing the housing to bemounted using screws or other fasteners that extend through the holes orslots. In this manner, the modules may be oriented in a large number ofdifferent arrangements to facilitate interconnection while optimizingspace utilization within a given cabinet design.

The housing structures may also include mounting features for othercomponents, such as snubber resistors and capacitors and voltage sharingresistors, including cone shaped structures to accommodate dimensionaltolerance variations in tubular power resistor sizes, etc. The coneshaped resistor supports may be slotted to allow the supports to flex toaccommodate dimensional variations in the size of the snubber or sharingresistors. In addition, the housing structures may provide driversupport structures for mounting the driver boards in two or moreorientations on the exterior of the housing, to thereby increase theflexibility in wiring cables to the modules in a given modular softstarter configuration.

The two housing structures are preferably made of non-conductive moldedmaterial and are joined along a closure line that extends around two ormore sides of the housing in a closure plane. The closure, moreover, mayinclude mating ribs and grooves along the closure line of the twohousing structures to provide voltage separation between the module andadjacent components within a given cabinet structure. The housingstructures in one embodiment include closure structures with holes formounting the housing structures together using fasteners extendingthrough the holes. In certain implementations, these housing closurestructure holes are adapted for use with self-tapping screws, and mayalso include hexagonal recesses to receive hex nuts for assembling thehousing structures via screws extending through the holes to engage thehex nuts.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and drawings set forth certain illustrativeimplementations of the invention in detail, which are indicative ofseveral exemplary ways in which the principles of the invention may becarried out. The illustrated examples, however, are not exhaustive ofthe many possible embodiments of the invention. Other objects,advantages and novel features of the invention are set forth in thefollowing detailed description of the invention when considered inconjunction with the drawings, in which:

FIG. 1A is a perspective view illustrating an exemplary soft startermodule in accordance with one or more aspects of the present disclosurewith first and second housing structures shown separated;

FIG. 1B is a bottom plan view illustrating the first or top housingstructure in the module of FIG. 1A showing the groove and rib closureseal features thereof;

FIG. 1C is a top plan view illustrating the second or bottom housingstructure in the module of FIG. 1A showing the mating rib and grooveseal features;

FIG. 2A is a front elevation view illustrating the assembled softstarter module with two separate gate driver circuit boards mountedhorizontally on the exterior of the front side of the module with onedriver board on each of the first and second housing structures;

FIG. 2B is a side elevation view illustrating the assembled soft startermodule;

FIG. 2C is a bottom plan view of the assembled soft starter module;

FIG. 2D is a rear elevation view illustrating the assembled soft startermodule;

FIG. 3A is a front elevation view illustrating an alternate embodimentof the assembled soft starter module with two separate gate drivercircuit boards mounted vertically across the front sides of the firstand second housing structures;

FIG. 3B is a perspective view of the assembled soft starter module ofFIG. 3A showing the soft starter components within the housing cavity;

FIG. 4 is a perspective view showing the interior of the first housingstructure;

FIG. 5 is a perspective view illustrating the first housing structurewith an SCR/heat sink stack structure removed from the housingstructure;

FIG. 6A is a perspective view illustrating an upper portion of the firsthousing structure showing cone shaped resistor supports in the housinginterior;

FIG. 6B is a perspective view illustrating an upper portion of analternate embodiment of the first housing structure showing slotted coneshaped resistor supports;

FIG. 7 is a perspective view illustrating the upper portion of the firsthousing structure showing two sets of driver board support structuresfor mounting the driver boards on the exterior of the housing usingstandoff inserts;

FIG. 8 is a rear perspective view illustrating the upper portion of thefirst housing structure showing insertion of a standoff insert into adriver support slot structure;

FIG. 9 is a schematic view illustrating interconnection of electricalcomponents of the exemplary soft starter module;

FIG. 10 is a simplified pictorial view illustrating the interconnectionof electrical components of the exemplary soft starter module;

FIG. 11A is front elevation view illustrating three soft starter modulesforming a three-phase soft starter;

FIG. 11B is a front elevation view showing an array of soft startermodules arranged with a plurality of modules connected in series foreach of three electrical motor phases to provide for increased voltagerating for the array;

FIG. 12A is a perspective view showing an exemplary soft starter modulearray configuration with the rear sides of the modules mounted to a flatsurface where the gate driver boards are mounted across the first andsecond housing structures;

FIG. 12B is a perspective view showing another exemplary soft startermodule array configuration with the bottoms of the modules mounted to aflat surface where the gate driver boards are mounted individually onthe housing structures;

FIG. 12C is a perspective view showing another possible arrayconfiguration in which the rear sides of the soft starter modules aremounted to a flat surface with the gate driver boards mountedindividually on the housing structures;

FIG. 12D is a perspective view showing an exemplary two level softstarter module array configuration with two rows of modules mounted backto back and top to bottom; and

FIG. 12E is a perspective view showing another exemplary soft startermodule array configuration with three columns of soft starter modulesmounted with their back sides to three different flat surfaces.

DETAILED DESCRIPTION

Referring now to the figures, several embodiments or implementations ofthe present invention are hereinafter described in conjunction with thedrawings, wherein like reference numerals are used to refer to likeelements throughout, and wherein the various features are notnecessarily drawn to scale. The invention provides a modular approach toconstruction and configuration of motor soft starters through theprovision of soft starter modules that can be mounted and interconnectedin different arrangements. In this manner, a given motor starterapplication with a set of voltage specifications can be accomplished byselection of the appropriate number of soft starter modules, and anyphysical space constraints can be managed through a choice of a numberof different mounting structures by which the modules can be mounted indifferent arrangements to economize space and ease serviceability.

An exemplary soft starter module 2 is shown partially opened in FIG. 1A,and fully assembled in FIGS. 2A-2D, where the module 2 constitutes asingle phase soft starter that can be combined with other like modules 2to create a soft starter for a multi-phase electric motor, asillustrated and described further below with respect to FIGS. 11A-12E.Each individual module 2 includes all of the electrical, control, andthermal components necessary to accommodate a single phase of a threephase motor controller, wherein the illustrated module 2 in one examplecan accommodate motor voltage ratings of up to 2400V. In this case,three such modules 2 can be employed to provide a soft starter for acomplete three phase soft starter power circuit up to 2400V.Furthermore, the modular design 2 allows construction of soft startersof greater voltage, in which case additional modules 2 are linked in aseries arrangement for each phase. In one example, six modules 2 can beserially connected for each of three phases to provide a motorcontroller for motors rated at 13.8KV.

As shown best in FIG. 1A, the exemplary module 2 comprises a housing 10including a first or upper housing structure 10 a and a second or lowerhousing structure 10 b made of non-conductive material, where thehousing structures 10 a, 10 b are preferably molded thermoplastics orother non-conductive material. The housing structures 10 a, 10 b, whenclosed or joined, define an interior cavity in which various softstarter circuit components are housed as best shown in FIG. 1A,including a power stack that includes two puck style SCR switchingdevices SCR1 and SCR2 interleaved between three aluminum or copper heatsinks HS1, HS2, and HS3, where the heat sink/SCR stack is connected withan anode of SCR1 coupled via the heat sink HS1 to a load terminal 12(FIG. 5) and a cathode coupled via HS2 to a line terminal 14. The secondswitching device SCR2 has an anode connected to the line terminal 14 viathe second heat sink HS2 as well as a cathode coupled with the loadterminal 12 via HS3, wherein the housing 10 provides external wiringaccess through corresponding openings to the load and line terminals 12and 14, respectively. In addition, the soft starter module 2 includesinternally mounted snubber resistors RS1, RS2, and RS3, a snubbercapacitor CS, and two sharing resistors RSH1 and RSH2, where the snubbercircuit components RS, as well as the sharing resistors RSH arepositioned and retained by features molded into the housing structures10 a and 10 b as further illustrated and described below.

The module 2 includes a driver apparatus such as a pair of gate drivercircuit boards GD1 and GD2 in one example that are electrically coupledvia appropriate wiring (not shown in FIG. 1A) to the gate terminals ofSCR1 and SCR2, respectively, and operate to provide switching controlsignals to the SCRs for selectively electrically connecting the lineterminal 14 with the load terminal 12 for operating an electric motor(not shown). As illustrated and described further below with respect toFIGS. 2A and 3A, the module 2 further provides for external mounting ofthe gate driver boards GD1 and GD2 in a plurality of differentorientations, including vertical mounting (FIG. 3A) and horizontalmounting (FIG. 2A). In the illustrated examples, the housing structures10 a and 10 b provide molded features 16 that accommodate the use of keyslot locking circuit board stand offs 80 for mounting the driver boardsGD1, GD2, where the molded driver support structures 16 in certainembodiments are undercut and open ended to allow the insertion of thestandoff 80.

Once assembled (e.g., FIGS. 2A-2D, 3A, and 3B), the two moldedstructures 10 a and 10 b are mechanically joined using fasteners such asself-tapping screws 94 (FIG. 1A), nuts and bolts, or other fasteningmeans. As shown in FIGS. 1A-1C, the upper and lower housing structures10 a, 10 b feature a series of ribs 60 and grooves 62 along a closureline where the structures 10 a, 10 b are joined, which cooperativelyinterweave to provide voltage separation between the module 2 andadjacent components. The interlacing of the exemplary grooves 62 andribs 60 along the housing closure line in one example provides anaccumulated surface tracking and through air distance sufficient towithstand overvoltage conditions expected in power systems with ratedvoltage up to and including 7.2 kV nominal. The housing 10 thus providesan interior cavity for protection and isolation of the internalcomponents, including the SCR/heat sink stack, wherein each housingsection 10 a, 10 b incorporates circular features 90 and slots 91 thataccommodate machined circular elements and clamp rods 42 c to providesupport and retention for in the SCR/heat sink assembly and allowpassage of the semiconductor clamp rods 42 c, as best shown in FIGS. 1A,1B, 4, and 5. The housing 10, moreover, provides at least one cavity tofully enclose the associated semiconductor clamp head 42 a, crossbar 42b, and clamping nuts 42 d threaded onto the clamp rods 42 c (FIG. 5)providing voltage isolation to surrounding components.

As shown in FIGS. 1B and 1C, the housing structures 10 a, 10 b furtherprovide integral features 50, 52, and 54 for locating and retaining thesharing and snubber resistors RSH, RS as well as the snubber capacitorCS, wherein the snubber capacitor CS retention structures 52 a and 52 bof the first and second housing structures 10 a and 10 b, respectively,include dual recesses to accommodate the variance in terminal diametersat either end of the capacitor CS. The resistor supports 50 and 54 ofthe housing structures 10 a and 10 b are sized to fit the internaldiameter of the tubular resistors and are tapered to provide a wedgingaction intended to prevent any free movement of the resistor and toaccommodate dimensional variations in resistor components RS and RSHwhile holding the resistors RS, RSH axially captive between therespective features in the two housing units 10 a and 10 b. As discussedbelow in connection with FIGS. 6A and 6B, the cone shaped structuresthemselves provide for dimensional tolerance variation accommodation dueto flexure in the structures 50, 54, and the cone shaped structures 50,54 may also be slotted (FIG. 6B) for further dimensional tolerancevariations in the resistors RS, RSH.

The housing structures 10, moreover, provide integral module mountingstructures 30, 32 for mounting the assembled module 2 in a variety ofphysical orientations, thereby facilitating optimal configuration of agroup of modules 2 with respect to minimizing space utilization,accessibility, etc. in a given cabinet design. As best shown in Figs.1Aand 3B, the module 2 exterior provides a top 20, a bottom 22, a first(front) side 24 a, a second side 24 b, a third (rear or back) side 24 c,and a fourth side 24 d. In the illustrated examples, a first set ofmodule mounting structures 32 a are provided on the first housingstructure 10 a allowing the housing 10 to be mounted to a flatstructure, such as a cabinet wall, floor panel, ceiling panel, etc. (notshown) with the top 20 generally parallel to the flat structure. Inaddition, the second housing structure 10 b includes an alternate set ofmodule mounting structures 32 b that allow the housing 10 to be mountedto a flat structure with the bottom side 22 generally parallel to theflat structure. Further, the module 10 can be mounted with the back side24 c to a flat structure via another set of module mounting structures30 on both the housing structures 10 a, 10 b. As illustrated anddescribed further below in connection with FIGS. 12A-12E, thesealternative module mounting structures 30, 32 facilitate adaptability ofthe modules 2 to a variety of different installation options. In thisregard, the module mounting structures 30 and 32 may also be used formounting one module 2 to another module 2, for example, as shown in FIG.12D below.

Referring now to FIGS. 4 and 5, the interior and front surface of theupper housing 10 a are shown, wherein the front side 24 a of housingstructure 10 a includes recessed slotted first driver support structures16 a as well as upper slotted driver support structures 16 b toaccommodate key slot locking circuit board standoffs 80 as shown furtherbelow in FIGS. 7 and 8. In addition, upper housing structure 10 aincludes flanged module mounting structures 30, comprising slottedopenings to allow passage of a threaded fastener for mounting the module10 to a flat surface. Flanges 32 a are also provide on the top of theupper housing structure 10 a, and which include holes for mounting thetop of the housing 10 to a flat structure. Inside the upper housingstructure 10 a, cone shaped resistor support structures 50 a areprovided which extent inwardly from the top surface of the first housingstructure 10 a for alignment and retention of the snubber resistorsRS1-RS3, along with cone shaped sharing resistor support structures 54 aand a snubber capacitor support structure 52 a. As further illustratedin FIGS. 4 and 5, the upper structure 10 a includes a series of inwardlyextending ribs 60 a as well as at least one groove 62 a, where the ribs60 a and groove 62 a extend along a closure line at which the upperhousing structure 10 a interfaces with the lower housing structure 10 b.In this example, the ribs 60 a and groove 62 a constitute a first sealstructure extending in a closure plane around three sides 24 b, 24 c,and 24 d, and a portion of the front side 24 a of the housing tent.

As further shown in FIGS. 4 and 5, the upper housing structure 10 aincludes housing closure structures 70 a with holes 72 a permittingmounting of the second housing structure 10 b to the first housingstructure 10 a using fasteners extending through the holes 72. In oneexample shown in FIG. 1A, self tapping screws 94 are used to join thetwo housing structures 10 a, 10 b wherein holes 72 a may be adapted tofixedly receive self tapping screws 94. In another possibleimplementation, the housing closure structures 70 a of the first housingstructure 10 a (and/or the housing closure structures 70 b of the secondhousing structure 10 b) include hexagonal recesses 74 (FIG. 2C) toreceive hex nuts (not shown) for mounting the second housing structure10 b to the first housing structure 10 a using screws extending throughthe hole 72 to engage the hex nuts.

As best shown in FIG. 5, moreover, the SCR/heat sink assembly 40 fitsinto the upper housing 10 a with the slots 91 in the interior of thehousing structure 10 a accommodating the clamp rods 42C and with thearcuate features 90 of the upper housing structure 10 a providing aseating surface for circular clamps structures 42E clamped to the outerheat sinks HS1 and HS3. When the SCR/heat sink assembly 40 is insertedinto the upper housing structure 10 a, line terminal 14 extends througha slot or other opening in the upper wall of housing structure 10 a toallow external wiring access and interconnection of the line terminal 14with other soft starter circuit components. Similarly, the load terminal12 in this embodiment includes a conductive metal structure clamped tothe outer heat sinks HS1 and HS3, for which external access is providedthrough an opening in the bottom surface of the lower housing structure10 b when the module 2 is assembled.

Referring now to FIGS. 6A and 6B, further details of an upper portion ofthe first housing structure 10 a are illustrated, including the abovedescribed first driver support structures 16 a and second driver supportstructures 16 b. Importantly, FIG. 6A and 6B show two differentembodiments of sharing resistor support structures 54 a. In particular,the sharing resistor support structures 54 a shown in FIG. 6A are coneshaped molded hollow structures extending inwardly to allow seating ofthe end of a tubular sharing resistor RSH, wherein the cone shape of thestructures 54 a permit retention and alignment of the sharing resistorsRSH1 and RSH2 even in the presence of dimensional tolerance variationsin the resistors RSH. This is accomplished, at least in part, throughthe combination of the conical shape of the structures 54 a and thethickness of the hollow cone walls in combination with the moldedmaterial (e.g., thermoplastics, etc.).

FIG. 6B shows an alternate implementation in which the conical resistorsupport structures 54 a include at least one slot extending at leastpartially along the axial length of the conical structures 54 a. Inanother possible embodiment, two such slots are provided atapproximately 90 degree angles to one another. The slotted configurationprovides two or more inwardly extending cone portions operative toengage the interior of the tubular resistors RSH, wherein the slottedconfiguration facilitates flexing of the supports 54 a to accommodatedimensional variations in the size of the sharing resistors RSH.Although the examples of FIGS. 6A and 6B illustrate conical slotted ornon slotted resistor support structures 54 a for mounting the sharingresistors RSH1 and RSH2, the snubber resistor mounting structures 50 ain the first housing structure 10 a (as well as the resistor mountingstructures 50 b and 54 b in the second housing structure 10 b) arelikewise cone shaped, and may preferably include slots, wherein all suchalternate implementations are contemplated as falling within the scopeof the appended claims.

Referring to FIG. 7 and 8, further details of the driver supportstructures 16 are shown in the upper portion of the first housingstructure 10 a, wherein the driver support structures 16 are similarlysituated on the second housing structure 10 b. As shown in FIG. 7, thefirst set of driver support structures 16 a may be used for mounting ofthe gate driver boards GD1 onto one of the housing structures 10 a, inwhich case circuit board standoffs 80 are inserted laterally into theslotted structure 16 a to allow subsequent mounting of the circuit board(not shown) onto the standoffs 80. In this configuration, one gatedriver board GD is mounted to each of the upper and lower housingstructures 10 a, 10 b (see for example FIG. 1A). In another possibleconfiguration, the standoffs 80 are inserted into the second set of gatedriver support structures 16 b, wherein two of the structures 16 b onthe upper housing 10 a will be used to support one end of a gate driverboard GD1, with the other end of the gate driver board GD1 beingsupported via standoffs 80 positioned in corresponding second driversupport structures 16 b of the lower second housing structure 10 b. FIG.8 illustrates a top perspective view of the upper housing structure 10 awith the upper wall thereof not shown, and further illustrates theplacement of one exemplary circuit board standoff 80 within one of theslotted first driver support structures 16 a.

Referring now to FIGS. 9 and 10, various electrical components of eachsoft starter module 2 are interconnected as shown, wherein the switchingdevices SCR1 and SCR2 are connected with an anode terminal of SCR1coupled through the first heat sink HS1 to the load terminal 12, and acathode terminal of SCR1 connected via heat sink HS2 to the lineterminal 14. The anode terminal of SCR2 is connected via heat sink HS2to the line terminal 14, and the cathode terminal of SCR2 is couple viaheat sink HS3 to the load 12. The driver boards GD1 and GD2 are coupledto control the switching operation of the devices SCR1 and SCR2,respectively, with driver board GD1 having a cathode and a gate outputconnected to control the gate terminal of SCR1. Similarly, driver boardGD2 has gate and cathode terminals tied to the control gate of SCR2. Inthe illustrated embodiment, three series connected snubber resistorsRS1, RS2, and RS3 are coupled in series with the snubber capacitor CSbetween driver board snubber terminals S1 and S2 of the driver boardsGD1 and GD2. Current sharing resistors RSH1 and RSH2 are seriesconnected between Cl and C2 terminals of the driver boards GD1 and GD2,where each of the sharing resistors RSH has a tap connected to overvoltage terminals of the corresponding driver boards GD1 and GD2,respectively.

Referring now to FIGS. 11A and 11B, three of the illustrated softstarted modules 2 may be employed to construct a three phase softstarter array 100, in which line power of each electrical phase isconnected to the line terminal 14 of the corresponding module 2 and themotor lead of that phase is connected to the load terminal 12 of themodule 2. FIG. 11A illustrates a low voltage modular soft starterincluding three such modules 2, wherein each phase module 2 is rated at2400 volts. This soft starter array 100 therefore may be employed toprovide a complete three phase soft starter power circuit for motorsrated up to 2400 volts. FIG. 11B illustrates another possible softstarter modular approach 100, in which motors of a higher voltage ratingare accommodated by linking addition modules to one another in seriesfor each phase. In this approach, a first module 2 of each phase has theline terminal 14 thereof connected to line power with the load terminal12 of the first module 2 connected to the line terminal 14 of the nextmodule 2, and succeeding modules are serially connected in this mannerwith the last module 2 having the load terminal 12 connected to themotor lead.

FIG. 12A shows a perspective view of one such modular array in whicheach phase includes six modules 2 serially connected to provide a motorcontroller for a motor rated at 13.8KV. In this embodiment, the rearsides 24C of each module 2 are mounted to a flat surface such as acabinet wall, cabinet floor, cabinet ceiling panel, etc., using thefirst set of module mounting structures 30 on the back sides of thefirst and second housing structures 10 a and 10 b. In thisimplementation, moreover, the gate driver boards GD1 and GD2 are mountedto the front sides 24 a of the modules 10, with each driver board GDbeing mounted to both the upper and lower housing structures 10 a and 10b via circuit board standoffs 80 located in the second driver supportstructure slots 16 b.

FIG. 12B shows another possible modular arrangement 100 in which sixmodules 2 are provided in each of the three motor phases, wherein thedriver boards GD1 and GD2 are individually mounted to a correspondingone of the housing structures 10 a and 10 b, using circuit boardstandoffs 80 located in the slotted first driver support structures 16a. In this configuration, the bottoms of the individual modules 2 aremounted to the flat surface using the second module mounting structures32 b of the lower housing structure 10 b.

FIG. 12C illustrates yet another possible configuration of the softstarter modules 2 to form an array configuration 100. In this example,the gate driver boards GD1 and GD2 are again mounted to individual onesof the housing structures 10 a, 10 b, with the modules being arranged instacks with the back side 24C of each module 2 being mounted to the flatsurface (such a panel wall) using the first set of module mountingstructures 30 (slotted flanges) and appropriate mounting screws. In thisconfiguration, moreover, the modules 2 within each of the columns may befastened to one another using screws or other fasteners extendingbetween the holes in the flanged second mounting structure 32 a of theupper housing structures 10 a and the holes of the second modularmounting structures 32 b of the lower housing structures 10 b.

FIG. 12D shows yet another soft starter 100 in which six modules 2 areagain employed for each of three electrical phases. In this case,however, each phase includes two vertical stacks of three modules 2 withthe lower two modules 2 being mounted to a lower flat surface of a panelusing module mounting structures 32 b of the lower housing structures 10b thereof. In addition, the two stacks of three modules 2 may be mountedback to back using fasteners extending through the slotted flange modulemounting structures 30 of each upper and lower housing structures 10 aand 10 b.

FIG. 12E illustrates yet another example configuration 100 in whichthree stacks of six modules 2 are provided for a corresponding threephase drive system. In this example, each phase may be mounted to adifferent vertical surface using the slotted mounting structures 30 atthe back sides 24C of each of modules 2.

The above implementations are merely examples of several possibleembodiments of various aspects of the present invention, whereinequivalent alterations and/or modifications will occur to others skilledin the art upon reading and understanding this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described components assemblies, devices,systems, circuits, and the like, the terms including a reference to a“means” used to describe such components are intended to correspond,unless otherwise indicated, to any component, such as hardware,software, or combinations thereof, which performs the specified functionof the described component i.e., that is functionally equivalent, eventhough not structurally equivalent to the disclosed structure whichperforms the function in the illustrated implementations of theinvention. In addition, although a particular feature of the inventionmay have been disclosed with respect to only one of severalimplementations, such feature may be combined with one or more otherfeatures of the other implementations as may be desired and advantageousfor any given or particular application. Also, to the extent that theterms “including”, “includes”, “having”, “has”, “with”, or variantsthereof are used in the detailed description and/or in the claims, suchterms are intended to be inclusive in a manner similar to the term“comprising”.

1. A soft starter module for selectively electrically connecting a powerline terminal with an electric motor load terminal, the modulecomprising: a first switching device having a first terminalelectrically coupled with a load terminal and a second terminalelectrically coupled with a line terminal; a second switching devicehaving a first terminal electrically coupled with the line terminal anda second terminal electrically coupled with the load terminal; a driverapparatus providing switching control signals to the first and secondswitching devices for selectively electrically connecting the lineterminal with the load terminal; and a housing with a top, a bottom, andat least one side, the housing comprising: a first housing structure, asecond housing structure mounted to the first housing structure, thefirst and second housing structures defining a cavity in which the firstand second switching devices are mounted and allowing for externalaccess to the load terminal and the line terminal, at least one of thefirst and second housing structures including driver support structuresfor mounting the driver apparatus to the housing, a first set of modulemounting structures located on at least one of the first and secondhousing structures and allowing the housing to be mounted to a flatstructure with a first one of the top, the bottom, and the at least oneside generally parallel to the flat structure; and a second set ofmodule mounting structures located on at least one of the first andsecond housing structures and allowing the housing to be mounted to theflat structure with a second one of the top, the bottom, and the atleast one side generally parallel to the flat structure.
 2. The softstarter module of claim 1, wherein the driver apparatus comprises afirst driver board providing switching control signals to the firstswitching device, and a second driver board providing switching controlsignals to the second switching device; and wherein the first and secondhousing structures individually include first driver support structuresfor mounting one of the driver boards thereto, and second driver supportstructures for mounting the driver boards to both the first and secondhousing structures.
 3. The soft starter module of claim 2, wherein thefirst and second housing structures individually include driver supportstructures on a first side of the housing for mounting the driverapparatus to the first side of the housing, and wherein the first andsecond housing structures individually include first module mountingstructures on a different second side of the housing allowing thehousing to be mounted to a flat structure with the second side generallyparallel to the flat structure.
 4. The soft starter module of claim 1,wherein the first and second housing structures individually includedriver support structures on a first side of the housing for mountingthe driver apparatus to the first side of the housing, and wherein thefirst and second housing structures individually include first modulemounting structures on a different second side of the housing allowingthe housing to be mounted to a flat structure with the second sidegenerally parallel to the flat structure.
 5. The soft starter module ofclaim 1, wherein the module mounting structures include flanges on atleast one of the first and second housing structures, and wherein theflanges individually include at least one hole or slot allowing thehousing to be mounted to the flat structure with a fastener that extendsthrough the hole or slot.
 6. The soft starter module of claim 1, whereinthe first and second housing structures each include first modulemounting structures located on a side of the housing, and wherein atleast one of the first and second housing structures includes secondmodule mounting structures located on one of the top and the bottom ofthe housing.
 7. The soft starter module of claim 6, wherein the modulemounting structures comprise flanges that include at least one hole orslot allowing the housing to be mounted to the flat structure with afastener that extends through the hole or slot.
 8. The soft startermodule of claim 6, wherein the first housing structure includes a set ofsecond module mounting structures located on the top of the housingallowing the housing to be mounted to the flat structure with the topgenerally parallel to the flat structure, and wherein the second housingstructure includes a set of second module mounting structures located onthe bottom of the housing allowing the housing to be mounted to the flatstructure with the bottom generally parallel to the flat structure. 9.The soft starter module of claim 8, wherein the module mountingstructures comprise flanges that include at least one hole or slotallowing the housing to be mounted to the flat structure with a fastenerthat extends through the hole or slot.
 10. The soft starter module ofclaim 1, further comprising: a first heat sink connected to the firstterminal of the first switching device and to the load terminal; asecond heat sink connected to the second terminal of the first switchingdevice, to the first terminal of the second switching device, and to theline terminal; a third heat sink connected to the second terminal of thesecond switching device, and to the load terminal; and a clamp thatclamps the first heat sink, the first switching device, the second heatsink, the second switching device, and the third heat sink into a stackarrangement mounted in the cavity of the housing.
 11. The soft startermodule of claim 1, further comprising at least one snubber resistor andat least one snubber capacitor operatively coupled with the driverapparatus and located within the housing cavity.
 12. The soft startermodule of claim 11, wherein the at least one snubber resistor is atubular structure extending axially within the cavity between the firstand second housing structures, and wherein the first and second housingstructures individually include at least one resistor support extendinginto the cavity to engage the interior of an end of the snubberresistor.
 13. The soft starter module of claim 12, wherein the resistorsupports of the first and second housing structures are cone shaped. 14.The soft started module of claim 13, wherein the cone shaped resistorsupports of the first and second housing structures include slotsallowing the supports to flex to accommodate dimensional variations inthe size of the snubber resistor.
 15. The soft starter module of claim11, wherein the at least one snubber capacitor is a cylindricalstructure extending axially within the cavity between the first andsecond housing structures, and wherein the first and second housingstructures individually include at least one capacitor support extendinginto the cavity to engage the end of the snubber capacitor.
 16. The softstarter module of claim 1, further comprising at least one sharingresistor coupled between the line terminal and the load terminal andlocated within the housing cavity.
 17. The soft starter module of claim16, wherein the at least one sharing resistor is a tubular structureextending axially within the cavity between the first and second housingstructures, and wherein the first and second housing structuresindividually include at least one resistor support extending into thecavity to engage the interior of an end of the sharing resistor.
 18. Thesoft starter module of claim 17, wherein the resistor supports of thefirst and second housing structures are cone shaped.
 19. The softstarted module of claim 18, wherein the cone shaped resistor supports ofthe first and second housing structures include slots allowing thesupports to flex to accommodate dimensional variations in the size ofthe sharing resistor.
 20. The soft starter module of claim 1, whereinthe first and second housing structures are joined along a closure lineextending around a plurality of sides of the housing in a closure plane,wherein the first housing structure includes a first seal structurehaving at least two ribs and at least one groove between the ribs, theribs and the groove extending along the closure line, and wherein thesecond housing structure includes a second seal structure having atleast two ribs and at least one groove between the ribs, the ribs andthe groove extending along the closure line, and wherein one of the ribsof the first seal structure is within the groove of the second sealstructure when the first and second housing structures are joined alongthe closure line and one of the ribs of the second seal structure iswithin the groove of the first seal structure when the first and secondhousing structures are joined along the closure line.
 21. The softstarter module of claim 1, wherein the first and second housingstructures individually include a plurality of housing closurestructures with holes for mounting the second housing structure to thefirst housing structure using fasteners extending through the holes. 22.The soft starter module of claim 21, wherein the housing closurestructure holes of at least one of the first and second housingstructures are adapted to fixedly receive self-tapping screws to mountthe second housing structure to the first housing structure.
 23. Thesoft starter module of claim 21, wherein the housing closure structuresof at least one of the first and second housing structures includehexagonal recesses to receive hex nuts for mounting the second housingstructure to the first housing structure using screws extending throughthe holes to engage the hex nuts.